Although high resolution gamma ray spectrometry serves as the primary analytical technique in emergency response situations, chances for laboratories to practice analysing the type of spectra that may be expected in the early phase of such a situation are limited. This problem is more acute for laboratories in countries that have no nuclear facilities. The analysis of synthetically generated spectra may serve as a useful surrogate for actual spectra; this paper reports the results of a multilateral intercomparison exercise conducted using such a spectrum. Results indicate that the laboratories involved appear to have no problems identifying radioactive isotopes that regularly appear in national and international intercomparisons or exercises. However, some problems are evident for isotopes that are less often encountered which may, however, occur during the early phases of a nuclear accident. Isotopes prone to true coincidence summation proved also to be difficult with regard to correction of activities in some cases. The synthesized spectrum constituted a useful means of comparative analysis of complex spectra multilaterally without the impracticalities of using a sample drawn from a reactor.